The present invention concerns synergistic fungicidal mixtures. The present invention more particularly concerns synergistic mixture of xcex2-aminobutyric acid (hereinafter referred to as BABA) and its N-benzoyl-octyl ester derivatives for the control of plant diseases.
Fungicides are often combined in mixtures for 3 main reasons: 1. to widen the spectrum of antifungal activity to control several diseases occurring simultaneously in a crop 2. to exploit synergistic interaction between fungicides, by which the overall activity is increased and the concentration of the compounds reduced, and 3. to delay the selection process of resistant fungal individuals to one component of the mixture (Gisi, Phytopathology 86 1273-1279, 1996).
Avoidence of plant disease in agricultural production may be accomplished not only by using fungicides or fungicidal mixtures but also by using xe2x80x9cplant activatorsxe2x80x9d, molecules which enhance the natural resistance (defense) of the plant. Such activators which have no direct fungicidal effect on the pathogen (Ryals et al The Plant Cell 8: 1809-1819, 1996), induce systemic acquired resistance (SAR) in the plant several days after application (Ibid).
To date only few molecules were reported to induce SAR in crop plants viz. salicylic acid (SA), 2,6-dichloroisonicotinic acid (INA) benzol (1,2,3) thiadiazole-7-carbothiouic acid S-methyl ester (BTH) (Ibid), and DL-3-amino butyric acid (BABA, Cohen et al Plant Physiology 104: 56-59, 1994).
However whereas SA, INA or BTH have to be applied to the crop ahead of infestation (Ryals, et al Ibid) BABA can be applied postxe2x80x94infectionaly (Cohen et al Ibid).
The idea behind the present invention is to combine two methods of disease controlxe2x80x94the directxe2x80x94kill method operating on the target pathogen and the indirect method of activating the natural defense approach of the crop plant. Such two methods are combined by using mixtures of a fungicide or fungicides (directxe2x80x94kill) with BABA or its N-benzoyl-octyl ester derivative(SAR).
We show here that such mixtures are synergistic in controlling plant diseases.
It is the objective of the present invention to provide novel mixtures of fungicides of xcex2-aminobutyric acids. It is an objective of the present invention to provide a synergistic mixture of BABA and/or its N-benzoyl-octyl ester derivative with various other fungicides.
In accordance with the present invention there is provided synergistic fungicidal compositions comprising one or more compounds selected from Group A and one or more compounds selected from Group B, wherein the compounds of Group A are selected from the group consisting of DL-3 aminobutyric-acid and its N-Benzoyl octyl ester, and the compounds of Group B are selected from the group consisting of fosetyl aluminum, dimethomorph, a mixture of folpet and ofturace (45:5), folpet, fencaramid (Bayer SZX), mancozeb, cymoxanil, methalaxyl, the single optical isomer of metalaxyl, a mixture of cymoxamil and mancozeb (4:1), copper sulfate, copper hydroxide, copper sulfate hydrate, azoxystrobin, and acibenzolar-s-methyl.
The present invention also provides an improved method of controlling fungi, especially late blight and downy mildews, applying to the plant a composition containing an effective amount of one of these mixtures. The present invention further provides an improved method of controlling phytophthora infertan in potato or tomatoe, Pseudoperonospora cubensis in cucumber or melon, Plasmopera viticola in grapes, and Peronospora tabacina in tabacco.